If I sign up for Part D during Medicare enrollment, how soon does the coverage start to take effect?

When you sign up for a Part D plan, the date the coverage becomes effective depends on which enrollment period you used to sign up for your Part D plan.

  • If you sign up for a Part D plan during the Annual Enrollment Period, which runs from October 15th through December 7th, your coverage will be effective January 1st of the following year.
  • If you sign up for a Part D plan during the Open Enrollment Period (OEP), there are only certain situations in which you can do this, which runs from January 1st through March 31st; the coverage will be effective the first of the month after you submit your enrollment. For example, if you sign up in January, your Part D coverage will be effective February 1st.
  • If you sign up when you turn 65 during your Initial Enrollment Period (IEP), your coverage will be effective the first of the month of your birthday month. For example, if you turn 65 on September 8th and submit your enrollment application in August, your Part D plan will be effective on September 1st.
  • If you turned 65 but were still working and deferred your enrollment in Medicare because you had health insurance provided by your employer, your coverage will begin the first of the month following your enrollment in a Part D plan.
  • If you enroll in a Part D plan during a Special Enrollment Period (SEP). The effective date of your coverage will generally be the first of the month following your enrollment in a Part D plan.